This invention relates to a novel control mechanism, and more particularly to a control mechanism for controlling both the clutch and throttle of marine engine by a single lever.
Control mechanism of the type employing a single lever needs to be readily operable free from troubles even by unskilled persons and therefore must fulfill the essential requirements of being so adapted that a throttle is held out of operation until a clutch of engine is completely shifted and having a construction by which the clutch is always held in the shifted position thereof during the operation of the throttle. Further, cheapness and compactness in size are another essential requirements in addition to the security, durability and operability in case of applying it for engine of comparatively small power, such as motorboat engine.
With reference to known control mechanism of the type, the inventor of the present invention found another important problem to be dissolved which results from the clutch mechanism of engine per se.
The clutch of engine of many types, generally, are constructed in such a manner that the shifting thereof is performed by virtue of meshing and releasing engagement between the helical gears contained therein. And the gears are apt to produce a pulling or pushing force which originates from the tendency of the gears of being separated each other, and the force is applied on the clutch arm of the control mechanism through a connecting device such as a clutch cable during and even after the shifting engagement thereof.
On the other hand, in the known control mechanisms previously proposed such as those disclosed in U.S. Ser. Nos. 2,907,421, 2,935,891, 2,973,069, 2,884,109 and 3,858,699, the shifting of the clutch of engine is performed by turning the clutch arm about 30.degree. to 60.degree. in either direction from the neutral position and none of them has a clutch arm which is turnable about 90.degree..
Therefore, in the previous control mechanisms, the aforesaid force produced at the clutch of engine and transmitted to the clutch arm through the clutch rod, constantly causes the torsional moment to the axle to which the clutch arm is secured, even after the clutch is fully shifted and held in the shifted positions thereof, as will be evident as the discription proceeds. The torsional moment often causes a locking member which is employed for holding the clutch in its shifted positions during the operation of the throttle and is fixed on the axle, to indiscriminately impinge against an opposing locking member and to thereby produce a noise, and results in greater stress on the both locking member with subsequently wear and it consequently shortens the lifetime or durability thereof.
Further, in the previous control mechanisms provided with a clutch arm which is turnable only about 30.degree. to 60.degree. since the necessary torque for rotating the lever varies suddenly when the clutch arm is locked against turning by virtue of the locking engagement between the two aforesaid locking members (or in other words, since the clutch arm is in halt in the shifted position and therefore the torsional moment applied constantly on the clutch arm comes not so as to affect the lever instantly any more), the feeling of operation for the control mechanism is deteriorated.
What is worse still, when returning the lever which is further rotated beyond the shifted position of clutch toward the neutral position, a serious shock load is produced thereupon, since the both aforesaid locking members come into contact with each other prior to the disengaging therebetween and prior to the rotation of the axle which is locked against rotation at the shifted position and on which the torsional moment is applied constantly. Additionally, after that, the aforesaid variation of torque for operating the lever occurs again.
With respect to the shock load, it should be reduced to minimum, since the shock load introduces an unwanted shock to the operator, in addition to the useful shock for indicating him the shifted positions of clutch by feel of frictional engagement of the suitable means which may be preferably composed of a spring-biased ball detent and a recesses.
These two shocks, which are so called two-step-shocks are quite unfavorable for the operator, since they sometimes make him misunderstand the shifting position of the clutch of engine.
And further the strength of unwanted shock is increased with the aforesaid wearing of the locking members, owing to the force applied constantly thereon through the clutch arm in the previous control mechanism.
In the control mechanism of the present invention, since the clutch arm is so constructed that it is turnable about 90.degree. in either direction from the neutral position and therefore the clutch rod connected to the clutch arm and the clutch arm pass near the center of the axle when the clutch is shifted in alternate positions, the aforesaid force produced at the clutch of engine does not apply any torsional moment on the axle. Therefore, the axle which is in the shifted position is turnable smoothly without employing any additional torque and without producing any variation in torque for rotation of clutch arm. Therefore, the excellent effects below described are obtainable in the control mechanism in the invention.
(1) The operation for shifting the clutch is performed quite smoothly, even when returning the lever which is turned beyond the shifted positions toward the neutral position.
(2) The locking members which are in contact with each other for holding the clutch in its shifted positions have a long durability, since the stress therein applied when they are in contact relation and the wearing thereof are extremly small.
(3) When returning the level turned beyond the shifted positions toward the neutral position, any unfavorable or unwanted shock is never produced thereupon, since any torsional moment is not applied on the axle at the shifted positions and the axle is turnable softly without employing any additional torque therefor, and consequently the locking members come into contact each other without producing a shock load.
Further, unexpected excellent features are also obtainable.
(4) The control mechanism of the present invention can be formed in small-sized, since the clutch arm is turnable about 90.degree. in either direction from the neutral position (about 180.degree. in all total) and therefore the radial distance of the clutch arm which is necessary for shifting the clutch of engine can be reduced to minimum.
(5) The inner wire of the clutch cable of the control mechanism of the present invention practically does not move longitudinally at the end period of the shifting of clutch, since the clutch cable passes near the center of the axle and the swivel connection which is pivoted at the end of the clutch arm undergoes a circular arc motion. Consequently, the inner wire of the cable is not substantially pulled lengthwise after the accomplishment of shifting of clutch and is not applied any excessive force thereupon and therefore a trouble such as breaking of the wire is effectively avoidable.